Lines

• Parallel lines - lines that never intersect; same slope

  • 2 lines y = m₁ + b₁, and y = m₂ + b₂ are parallel if m₁ = m₂

    • ex; 3x + 1, 3x - 6;

    • 3 = 3, equal

• Perpendicular lines - lines that intersect at a 90° angle; opposite reciprocal slopes

  • 2 lines y = m₁ + b₁, and y = m₂ + b₂ are perpendicular if m₁ = -1/m₂

    • ex; x + 1, -x - 2;

    • 1 = -1/-1, opposite reciprocal

SOLVE 7y = x, 7x = 3 - y; is this perpendicular

• y = x/7 + 0, y = -7x + 3

  x/7 = -1/-7 =

  1x/7 = 1/7; yes